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This dissertation explores the economic consequences of wildfire and smoke in the United States. The third chapter, Wildfire smoke in the United States, is joint work with Matthew Wibbenmeyer, and examines regional and temporal trends in wildfire smoke impacts. It synthesizes research on health, economic, and behavioral impacts, proposing modifications to federal air quality regulations to address wildfire smoke. The second chapter, Wildfire, smoke, and outdoor recreation in the western United States, is a collaboration with Margaret Walls and Matthew Wibbenmeyer. It focuses on the effects of wildfire and smoke for outdoor recreation. The paper combines millions of administrative campground reservation records with daily satellite data on wildfire, smoke, and air pollution, finding that more than ten percent of available recreation days are affected by severe smoke in some regions. The first chapter, Non-market damages of wildfire smoke: evidence from administrative recreation data, is also a collaboration with Margaret Walls and Matthew Wibbenmeyer. This chapter exploits the dataset of the second chapter to provide among the first revealed preference estimates of smoke damages. A structural model of sequential recreation decisions finds that smoke reduces welfare by $107 per person per trip. Annually, more than 21.5 million outdoor visits in the western United States are affected by wildfire smoke, with welfare losses of $2.3 billion. These findings contribute to a growing body of evidence on the costs of wildfire smoke.

Wildfires and extreme heat events are inherently linked; shared climatic drivers are simultaneously worsening both hazardous events in California. Populations likely experience exposure to a combination of these hazards, i.e., compound hazards; yet there is little known about this public health threat. Studies indicate wildfire smoke and extreme heat, independently, elevate risks for morbidity and mortality. In addition, epidemiologic evidence gives reason to suspect compound wildfire smoke and extreme heat could exacerbate health outcomes and present a greater threat to public health.This dissertation aims to examine multiple facets of compound wildfire smoke and extreme heat in California. Chapter one assesses the distribution of compound wildfire smoke and extreme heat exposures in California from 2011-2020. The exposure assessment uses a clinically meaningful definition of exposure to estimate populations with disproportionate vulnerabilities. Chapter two then estimates the joint effects of exposure to wildfire smoke and extreme heat within a short-term exposure lag window. Chapters two and three both utilize a statewide payer’s database to examine all-natural cause, cardiovascular, cerebrovascular, renal, and respiratory morbidity impacts. In Chapter three, exposures are examined at different time periods to evaluate temporally compounding wildfire smoke and extreme heat in two ways; that is, effect modification of extreme heat-related morbidity by wildfire smoke exposure weeks to months prior, and vice versa. Methods include descriptive mapping and exposure assessment to identify disproportionately exposed populations. Joint effects and effect modification are estimated using time-stratified case crossover design with conditional logistic regression models. Each chapter investigates different periods of exposure and characterizes findings by individual or community level factors, such as race and ethnicity, income, education, and rural and urban classification

The results of two previously published reports of the events and impacts of the Campfire wildfire smoke exposure that occurred in California in 2018 are amplified from the point of view of the potential toxic mechanism involved. The Campfire wildfire led to the exposure of a breeding colony of macaque monkeys (Macaca mulatta) during the peak of their breeding season in 2018-2019. Considering the timing, adverse effects, and endocrine implications reported, the cumulative evidence points to an early toxic sensitive period that can lead to birth defects in higher primates and human pregnancies. This deeper inspection of the published observations provides important caveats and useful guidance for future investigators. The unique higher primate placental-adrenal-brain axis may limit the use of many traditional toxicologic approaches. Retrospective neurological evaluations of human fetuses exposed to air pollutants during organogenesis and subsequent retrospective characterization of air samples using in vitro and animal models may be the best procedures to follow.

Wildfires are a significant source of volatile organic compounds (VOCs) in the western U.S., emitting hundreds to thousands of different species that play key roles in tropospheric oxidation, ozone production, and secondary organic aerosol formation. Many of these VOCs have only recently been identified and quantified in laboratory burning experiments. Consequently, little is known about their emissions from wildfires, which species are most important for plume OH oxidation chemistry, and how they evolve as smoke plumes age. This dissertation aims to improve our understanding of the emissions and chemistry of VOCs in wildfire smoke using detailed in situ measurements made during the summer 2018 Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN) field campaign. WE-CAN sampled wildfire smoke across seven western states and is one of the most comprehensive field studies of smoke emissions and aging to date. During the campaign, VOCs were measured by four complementary instruments, which were all found to agree within their stated uncertainties for most co-measured species. Leveraging these measurements, we report emission factors (EFs) and emission ratios (ERs) for 161 VOCs measured from 24 individual fires (Permar et al., 2021). OH reactivity (OHR) was used to determine which species are most important for daytime plume OH chemistry, and therefore should be included in next generation atmospheric chemistry models. From this, the master chemical mechanism was determined to contain chemistry for most reactive species. However, ~50 % of the emitted VOC OHR is not currently implemented in the commonly used GEOS-Chem chemical transport model. Implementing chemistry for furan-containing species, butadienes, and biomass burning monoterpenes would greatly improve model representation (Permar et al., 2023). As smoke plumes age, formic acid was rapidly produced at rate of 2.7 ppb ppmCO-1 h-1, resulting in it and acetic acid become an incr

BackgroundWildfire smoke is responsible for around 20% of all particulate emissions in the U.S. and affects millions of people worldwide. Children are especially vulnerable, as ambient air pollution exposure during early childhood is associated with reduced lung function. Most studies, however, have focused on the short-term impacts of wildfire smoke exposures. We aimed to identify long-term baseline epigenetic changes associated with early-life exposure to wildfire smoke. We collected nasal epithelium samples for whole genome bisulfite sequencing (WGBS) from two groups of adult female rhesus macaques: one group born just before the 2008 California wildfire season and exposed to wildfire smoke during early-life (n = 8), and the other group born in 2009 with no wildfire smoke exposure during early-life (n = 14). RNA-sequencing was also performed on a subset of these samples.ResultsWe identified 3370 differentially methylated regions (DMRs) (difference in methylation ≥ 5%, empirical p < 0.05) and 1 differentially expressed gene (FLOT2) (FDR < 0.05, fold of change ≥ 1.2). The DMRs were annotated to genes significantly enriched for synaptogenesis signaling, protein kinase A signaling, and a variety of immune processes, and some DMRs significantly correlated with gene expression differences. DMRs were also significantly enriched within regions of bivalent chromatin (top odds ratio = 1.46, q-value < 3 × 10-6) that often silence key developmental genes while keeping them poised for activation in pluripotent cells.ConclusionsThese data suggest that early-life exposure to wildfire smoke leads to long-term changes in the methylome over genes impacting the nervous and immune systems. Follow-up studies will be required to test whether these changes influence transcription following an immune/respiratory challenge.

Wildfire smoke is an increasing environmental health threat to which children are particularly vulnerable, for both physiologic and behavioral reasons. To address the need for improved public health messaging this review summarizes current knowledge and knowledge gaps in the health effects of wildfire smoke in children, as well as tools for public health response aimed at children, including consideration of low-cost sensor data, respirators, and exposures in school environments. There is an established literature of health effects in children from components of ambient air pollution, which are also present in wildfire smoke, and an emerging literature on the effects of wildfire smoke, particularly for respiratory outcomes. Low-cost particulate sensors demonstrate the spatial variability of pollution, including wildfire smoke, where children live and play. Surgical masks and respirators can provide limited protection for children during wildfire events, with expected decreases of roughly 20%  and 80% for surgical masks and N95 respirators, respectively. Schools should improve filtration to reduce exposure of our nation's children to smoke during wildfire events. The evidence base described may help clinical and public health authorities provide accurate information to families to improve their decision making.

IntroductionWildfire smoke (WFS) exposure is a growing threat to human health, and lower socioeconomic position (SEP) has been shown to increase pollution susceptibility. Studies of SEP-related susceptibility, however, are often compromised due to spatial confounding between lower-SEP and pollution. Here we examine outdoor-housed nonhuman primates, living in natural social hierarchy in a common location, born during years of high vs. low WFS, to examine the separate and combined effects of WFS and social rank, an analog to SEP, on lung and immune function.MethodsTwenty-one females were born during extreme WFS events in summer 2008; 22 were born in summer 2009, during low WFS. Pulmonary function and circulating cytokines were measured three years later, in adolescence. We estimated fine particulate (PM2.5) and ozone exposures during each animal's first 90 days and three years of age using regulatory data. Early-life social status was estimated using maternal rank at birth, as rank in females is relatively stable throughout life, and closely approximates mother's rank. We tested associations among WFS exposure, rank, and endpoints using linear regression and ANOVA.ResultsHigher WFS exposure in infancy was, on average, associated with lower functional residual capacity (FRC), residual volume (RV), tissue compliance (Ct), and IL-8 secretion in adolescence. Higher social rank conferred significantly higher expiratory reserve volume (ERV) and functional residual capacity (FRC) solely among those born in the high-WFS year (2008). Differences in effects of rank between years were not significant after adjustment for multiple comparisons.ConclusionsExposure to WFS in infancy generally conferred lower adolescent respiratory volumes and inflammatory cytokines. Higher rank conferred higher respiratory volumes only among females born during WFS, suggesting the possibility that the health benefits of rank may be more apparent under environmental challenge.

Wildfire smoke is an increasing environmental health threat to which children are particularly vulnerable, for both physiologic and behavioral reasons. To address the need for improved public health messaging this review summarizes current knowledge and knowledge gaps in the health effects of wildfire smoke in children, as well as tools for public health response aimed at children, including consideration of low-cost sensor data, respirators, and exposures in school environments. There is an established literature of health effects in children from components of ambient air pollution, which are also present in wildfire smoke, and an emerging literature on the effects of wildfire smoke, particularly for respiratory outcomes. Low-cost particulate sensors demonstrate the spatial variability of pollution, including wildfire smoke, where children live and play. Surgical masks and respirators can provide limited protection for children during wildfire events, with expected decreases of roughly 20%  and 80% for surgical masks and N95 respirators, respectively. Schools should improve filtration to reduce exposure of our nation's children to smoke during wildfire events. The evidence base described may help clinical and public health authorities provide accurate information to families to improve their decision making.

IntroductionWildfire smoke (WFS) exposure is a growing threat to human health, and lower socioeconomic position (SEP) has been shown to increase pollution susceptibility. Studies of SEP-related susceptibility, however, are often compromised due to spatial confounding between lower-SEP and pollution. Here we examine outdoor-housed nonhuman primates, living in natural social hierarchy in a common location, born during years of high vs. low WFS, to examine the separate and combined effects of WFS and social rank, an analog to SEP, on lung and immune function.MethodsTwenty-one females were born during extreme WFS events in summer 2008; 22 were born in summer 2009, during low WFS. Pulmonary function and circulating cytokines were measured three years later, in adolescence. We estimated fine particulate (PM2.5) and ozone exposures during each animal's first 90 days and three years of age using regulatory data. Early-life social status was estimated using maternal rank at birth, as rank in females is relatively stable throughout life, and closely approximates mother's rank. We tested associations among WFS exposure, rank, and endpoints using linear regression and ANOVA.ResultsHigher WFS exposure in infancy was, on average, associated with lower functional residual capacity (FRC), residual volume (RV), tissue compliance (Ct), and IL-8 secretion in adolescence. Higher social rank conferred significantly higher expiratory reserve volume (ERV) and functional residual capacity (FRC) solely among those born in the high-WFS year (2008). Differences in effects of rank between years were not significant after adjustment for multiple comparisons.ConclusionsExposure to WFS in infancy generally conferred lower adolescent respiratory volumes and inflammatory cytokines. Higher rank conferred higher respiratory volumes only among females born during WFS, suggesting the possibility that the health benefits of rank may be more apparent under environmental challenge.

Fine particulate matter (PM2.5) raises human health concerns since it can deeply penetrate the respiratory system and enter the bloodstream, thus potentially impacting vital organs. Strong winds transport and disperse PM2.5, which can travel over long distances. Smoke from wildfires is a major episodic and seasonal hazard in Southern California (SoCal), where the onset of Santa Ana winds (SAWs) in early fall before the first rains of winter is associated with the region's most damaging wildfires. However, SAWs also tend to improve visibility as they sweep haze particles from highly polluted areas far out to sea. Previous studies characterizing PM2.5 in the region are limited in time span and spatial extent, and have either addressed only a single event in time or short time series at a limited set of sites. Here we study the space-time relationship between daily levels of PM2.5 in SoCal and SAWs spanning 1999-2012 and also further identify the impact of wildfire smoke on this relationship. We used a rolling correlation approach to characterize the spatial-temporal variability of daily SAW and PM2.5. SAWs tend to lower PM2.5 levels, particularly along the coast and in urban areas, in the absence of wildfires upwind. On the other hand, SAWs markedly increase PM2.5 in zip codes downwind of wildfires. These empirical relationships can be used to identify windows of vulnerability for public health and orient preventive measures.

Fine particulate matter (PM2.5) raises human health concerns since it can deeply penetrate the respiratory system and enter the bloodstream, thus potentially impacting vital organs. Strong winds transport and disperse PM2.5, which can travel over long distances. Smoke from wildfires is a major episodic and seasonal hazard in Southern California (SoCal), where the onset of Santa Ana winds (SAWs) in early fall before the first rains of winter is associated with the region's most damaging wildfires. However, SAWs also tend to improve visibility as they sweep haze particles from highly polluted areas far out to sea. Previous studies characterizing PM2.5 in the region are limited in time span and spatial extent, and have either addressed only a single event in time or short time series at a limited set of sites. Here we study the space-time relationship between daily levels of PM2.5 in SoCal and SAWs spanning 1999-2012 and also further identify the impact of wildfire smoke on this relationship. We used a rolling correlation approach to characterize the spatial-temporal variability of daily SAW and PM2.5. SAWs tend to lower PM2.5 levels, particularly along the coast and in urban areas, in the absence of wildfires upwind. On the other hand, SAWs markedly increase PM2.5 in zip codes downwind of wildfires. These empirical relationships can be used to identify windows of vulnerability for public health and orient preventive measures.

Forests and trees may play important roles in human health outcomes and choices made by individuals in urban areas. Disruptions to forest amenities and tree canopy coverage caused by shocks to the natural environment may affect urban air quality, behavioral decisions, time use habits, and environmental management. This work exploits two distinct and unrelated shocks to forests in the United States to investigate the environmental and health economic links in urban areas between people and trees, and a proposed deeply ingrained role for environmental health in how people live, interact, optimize in their communities. The first chapter argues that environmental quality and forest amenities are important determinants of health and behavioral patterns in urban areas. The conclusion is that further investigations into the indirect market and nonmarket effects of forests and trees on the urban economy are necessary to better guide self-investments in health and management of natural resources. Chapter 2 examines one mechanism through which shocks to the natural environment caused by forest fires in the Mountain West affect health in high-density communities distant from the flame zone. Using a case study wildfire event in eastern Arizona that brought smoke over Albuquerque, New Mexico in 2011, this chapter advances the methodology by which wildfire smoke damages are assessed by modifying a relatively new US EPA benefit transfer computer program, coupling it with original household survey data, and demonstrating how it can be applied to wildfire smoke events. This chapter concludes that not only are wildfire smoke events costly in urban areas, but that perhaps wildfire smoke is more toxic to health than conventional urban air pollution, necessitating more deliberate and nuanced choices by analysts tasked with estimating the damages of wildfire events. Chapter 3 exploits a different shock to forest cover, caused by the emerald ash borer (EAB), to investigate heterogeneity i

Forests and trees may play important roles in human health outcomes and choices made by individuals in urban areas. Disruptions to forest amenities and tree canopy coverage caused by shocks to the natural environment may affect urban air quality, behavioral decisions, time use habits, and environmental management. This work exploits two distinct and unrelated shocks to forests in the United States to investigate the environmental and health economic links in urban areas between people and trees, and a proposed deeply ingrained role for environmental health in how people live, interact, optimize in their communities. The first chapter argues that environmental quality and forest amenities are important determinants of health and behavioral patterns in urban areas. The conclusion is that further investigations into the indirect market and nonmarket effects of forests and trees on the urban economy are necessary to better guide self-investments in health and management of natural resources. Chapter 2 examines one mechanism through which shocks to the natural environment caused by forest fires in the Mountain West affect health in high-density communities distant from the flame zone. Using a case study wildfire event in eastern Arizona that brought smoke over Albuquerque, New Mexico in 2011, this chapter advances the methodology by which wildfire smoke damages are assessed by modifying a relatively new US EPA benefit transfer computer program, coupling it with original household survey data, and demonstrating how it can be applied to wildfire smoke events. This chapter concludes that not only are wildfire smoke events costly in urban areas, but that perhaps wildfire smoke is more toxic to health than conventional urban air pollution, necessitating more deliberate and nuanced choices by analysts tasked with estimating the damages of wildfire events. Chapter 3 exploits a different shock to forest cover, caused by the emerald ash borer (EAB), to investigate heterogeneity i